We already know that the environment we live in can influence our sleep. Living in a bad neighborhood or a town with LED streetlights or high levels of air pollution can disrupt sleep. Some people even claim that living near wind farms makes sleep more difficult.
A 2017 study published in the International Journal of Environmental Research and Public Health now suggests that where you are born may also influence how much sleep you’re likely to get — and that moving to America may have a negative effect on your sleep.
Researchers collected data using the National Health Interview Survey (NHIS) — a yearly household interview conducted by the Centers for Disease Control and Prevention’s National Center for Health Statistics. The study extracted and analyzed data on self-reported sleep duration and place of birth, as well as information on factors related to disease risk such as body mass index, smoking status, and psychological distress.
Data was collected from 415,678 individuals over the age of 18 between 2003 and 2013. Of these, 16 percent were born outside the United States. Researchers found that foreign-born individuals were more likely to sleep for between seven and eight hours per day, compared to individuals born in the United States.
After adjusting for age, sex, race, education, alcohol use, smoking history, body mass index, exercise, diabetes, and coronary heart disease, researchers found that those born overseas were 19 percent more likely to get between seven and eight hours of sleep each day, compared to those born in the United States.
Sleep duration by place of birth
The study found that individuals were more likely to get between seven and eight hours of sleep if they were born in the following regions:
- Mexico, Central America, Caribbean Islands
- Indian Subcontinent
Only individuals born in Africa were found to have a significantly lower likelihood of getting between seven and eight hours of sleep compared to those born in the United States.
Perhaps most interestingly, researchers found that duration of time spent in the United States was correlated with sleep duration. In other words, the longer the amount of time foreign-born individuals spent in the United States, the less likely they were to enjoy a healthy sleep duration of between seven and eight hours.
Why is sleep duration influenced by our birthplace?
The authors of the study suggested the link between the amount of time a foreign-born individual spends in the United States and declining sleep duration may be explained by acculturation — as individuals become more integrated and accustomed to American culture, sleep duration declines.
Although the authors of the study did not suggest why this may be the case, the Western focus on work and accumulation of wealth, combined with the frequent disregard for the importance of sleep may play a role. Unfortunately, discrimination against immigrants may also have a negative impact on their sleep.
We can’t blame American and Western culture entirely, though.
The study pointed out that sleep durations may differ according to place of birth due to differences in circadian rhythms across racial and ethnic groups. For example, researchers highlighted previous studies that found individuals with African ancestry tended to have shorter sleep-wake cycles and were more likely to struggle to adjust when traveling west.
Environmental factors, such as how close we live to the equator can also affect the circadian rhythm (and consequently, our sleep). Those who live closer to the equator will generally be exposed to more natural sunlight compared to those who live further away. Exposure to light helps regulate the circadian rhythm and promotes melatonin production — an important sleep hormone.
Interestingly, the authors of this study suggested that since individuals from Mexico, the Indian subcontinent, and Southeast Asia tend to live in ethnically similar communities when in the United States, they may benefit from protection against stress related to acculturation — and therefore continue to enjoy healthy sleep for longer than those from other ethnic groups.
Although this research found that foreign-born individuals typically enjoy healthy sleep durations compared to those born in the United States, the longer they reside in America, the more likely that their sleep becomes compromised. We can look forward to future research digging deeper and investigating why this appears to be the case.
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Martin is the creator of Insomnia Land’s free insomnia sleep training. His online course uses CBT techniques to teach participants how to sleep better without relying on sleeping pills. More than 5,000 insomniacs have completed his course and 97 percent of graduates say they would recommend it to a friend.